This invention relates to the field of image processing technology for subjecting image data read photoelectrically from images on films by means of charge-coupled device (CCD) sensors and the like to specified image processing so that the read image data is converted to outputting image data.
Heretofore, the images recorded on photographic films such as negatives and reversals (which are hereunder referred to simply as xe2x80x9cfilmsxe2x80x9d) have been commonly printed on light-sensitive materials (photographic paper) by means of direct (analog) exposure in which the film image is projected onto the light-sensitive material to achieve its areal exposure.
A new technology has recently been introduced and this is a printer that relies upon digital exposure. Briefly, the image recorded on a film is read photoelectrically, converted to digital signals and subjected to various image processing operations to produce image data for recording purposes; recording light that has been modulated in accordance with the image data is used to scan and expose a light-sensitive material to record a latent image, which is subsequently developed to produce a (finished) print. The printer operating on this principle has been commercialized as a digital photoprinter.
In the digital photoprinter, images can be processed as digital image data so that exposure conditions at the time of printing can be determined. Accordingly, the digital photoprinter is capable of performing effective image processing operations such as the correction of washed-out highlights or flat (dull) shadows due to the taking of pictures with backlight, an electronic flash or the like, sharpening processing and the correction of color or density failures. Such image processing operations of the digital photoprinter enable to produce high-quality prints that reproduce images of the quality that has been impossible to achieve by the conventional direct exposure technique. Moreover, not only the assembling of images and the splitting of a single image into plural images but also the composition of characters can be performed by processing the image data. As a result, prints can be outputted after various editing and/or processing operations have been performed in accordance with specific uses in the digital photoprinter.
Outputting images as prints is not the sole capability of the digital photoprinter; the image data can be supplied into a computer or the like and stored in recording media such as a floppy disk; hence, the image data can be put to various non-photographic uses.
Having these features, the digital photoprinter is basically composed of the following units: an image inputting apparatus having a scanner (image reading apparatus) that reads the image recorded on a film photoelectrically and an image processing apparatus that processes the read image to produce output image data (exposure conditions); and an image outputting apparatus having a printer (image recording apparatus) that records a latent image on a light-sensitive material by scan exposing it in accordance with the image data supplied from the image inputting apparatus and a processor (developing apparatus) that performs development processing on the exposed light-sensitive material to produce a print.
In the scanner, reading light issued by a light source is allowed to be incident on a film, from which projected light bearing the image recorded on the film is produced and focused by an image forming lens to form an image on an image sensor such as a CCD sensor or the like. The image is then subjected to photoelectric conversion and sent to the image processing apparatus as the image data (image data signals) on the film after being optionally subjected to various kinds of image processing steps.
In the image processing apparatus, image processing conditions are set on the basis of the image data captured with the scanner and image processing in accordance with the thus set conditions is performed on the captured image data and the resulting output image data for image recording (i.e., exposing conditions) are sent to the printer.
In the printer, if it is of a type that relies upon exposure by scanning with an optical beam, the latter is modulated in accordance with the image data sent from the image processing apparatus and deflected in a main scanning direction as the light-sensitive material is transported in an auxiliary scanning direction perpendicular to the main scanning direction, whereby a latent image is formed as the result of exposure (printing) of the light-sensitive material with the image-bearing optical beam. In the processor, development and other processing in accordance with the light-sensitive material are performed to produce a print (photograph) reproducing the image that was recorded on the film.
In order to obtain high-quality prints, it is preferable that details of an image (image information) of a scene are recorded on a film as many and accurately as possible.
However, it is actually impossible to record all details of the scene on a film. Many image details (patterns) within over-exposed (excessively exposed) and under-exposed (insufficiently exposed) ranges cannot be recorded due to characteristic change (so-called characteristic deterioration) of the film.
Particularly, what unifies a lens and a film, so-called a one time use camera, or which is also called a single use camera, a film with lens or a snap shooting unit, cannot afford to install a variable diaphragm from a severe cost restriction so that the one time use camera is photographed over a wide exposure range. Accordingly, the one time use camera is liable to be under-exposed or over-exposed. In order to prevent the under-exposure, fitting up with an electronic flashing is an effective means, while no effective means exists to prevent over-exposure. Therefore, the one time use camera is liable to be over-exposed so that a high luminance region of a scene is easily sacrificed when the image is reproduced on a print.
An object of the present invention is to solve the above described problem in the prior art, and to provide an image processing method applicable to the above described digital photoprinter which reads an image recorded on a film photoelectrically, subjects the thus read image to an image processing and produces a print on which the image is reproduced, in which a high-quality image can be constantly obtained by suitably correcting the characteristic change of the film.
In order to achieve the above object, the present invention provides an image processing method for subjecting image data obtained by reading an image on a film photoelectrically to specified image processing, comprising the steps of:
acquiring film characteristic of said film; and
correcting the image data in accordance with the acquired film characteristic.
Preferably, said film characteristic is gradation characteristic of said film.
Preferably said film is for a one-time use camera.
Preferably, said correction step is a step of correction corresponding to deterioration of said film characteristic.
Preferably, said correction corresponding to the deterioration of said film characteristic is correction mainly in an over-exposed range of the film.
It is preferred that said acquiring step is at least one of a process of storing film characteristics of plural kinds of the film in a storing means and thereafter reading out a corresponding film characteristic from the storing means by detecting a kind of the film, a process of reading film characteristic information recorded on the film optically, a process of reading the film characteristic information recorded on the film magnetically and a process of inputting the film characteristic by an operator.
In this case, said film kind is, preferably, detected from the film by using at least one of an optical process and a magnetic process.
Preferably, said film characteristic is corrected by difference data between standard development conditions and adopted development conditions.
Characteristics in the under-exposed (or insufficiently exposed) range of the film can be anticipated to some extent by acquiring a mask density (density in an unexposed region), even if characteristics information of the film are not provided. On the other hand, characteristics in the over-exposed (or excessively exposed) range can hardly be anticipated without characteristics information corresponding to each film kind, since it is not known at what point gradation (xcex3) characteristics curve turns to decrease or to be dull. Accordingly, in the one time use camera which is liable to be over-exposed, it is preferable to store the film characteristics corresponding to each film kind, and then to detect and read out the film kind, thereby correcting image data in accordance with the read-out film kind.
Moreover, the film characteristics are affected by development conditions. Therefore, it is more preferable that the film characteristics are so arranged as to be corrected by the difference data acquired by comparing the development conditions adopted at lab shops and the standard ones.
Furthermore, though a detrimental effect appears such that roughness caused by graininess of the film is emphasized when characteristic change (so-called dull or deterioration of characteristics) of gradation in the under-exposed range is corrected, image deterioration caused by grains of the film is essentially small in the over-exposed range so that the detrimental effect, that is, emphasis of roughness, is kept relatively low even if the characteristic change in the over-exposed range are corrected.